21316265 has 4 divisors (see below), whose sum is σ = 25579524. Its totient is φ = 17053008.

The previous prime is 21316237. The next prime is 21316277. The reversal of 21316265 is 56261312.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 15594601 + 5721664 = 3949^2 + 2392^2 .

It is a cyclic number.

It is not a de Polignac number, because 21316265 - 2⁶ = 21316201 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2131622 + ... + 2131631.

It is an arithmetic number, because the mean of its divisors is an integer number (6394881).

Almost surely, 2^21316265 is an apocalyptic number.

It is an amenable number.

21316265 is a deficient number, since it is larger than the sum of its proper divisors (4263259).

21316265 is an equidigital number, since it uses as much as digits as its factorization.

21316265 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4263258.

The product of its digits is 2160, while the sum is 26.

The square root of 21316265 is about 4616.9540825094. The cubic root of 21316265 is about 277.2705242469.

Adding to 21316265 its reverse (56261312), we get a palindrome (77577577).

The spelling of 21316265 in words is "twenty-one million, three hundred sixteen thousand, two hundred sixty-five".